Re: Faster distinct query? - Mailing list pgsql-general

From David G. Johnston
Subject Re: Faster distinct query?
Date
Msg-id CAKFQuwZdBcBOi6mKnddeCjXjxXSmcLhdpiDSr+4Uuh+scmKwXg@mail.gmail.com
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In response to Re: Faster distinct query?  (David Rowley <dgrowleyml@gmail.com>)
Responses Re: Faster distinct query?  (David Rowley <dgrowleyml@gmail.com>)
List pgsql-general
On Wednesday, September 22, 2021, David Rowley <dgrowleyml@gmail.com> wrote:
I think writing the query in such a way
that allows it to be parallelised is likely going to result in some
quite good performance improvements. i.e:

Agreed, though if the query author needs to do that here we’ve violated the spirit of the declarative SQL language.  At first blush nothing about the original query seems like it should be preventing parallelism.  Each worker builds its own distinct array then the final concatenation is made distinct.

David J.

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